AC V-t and impulse V-N characteristics of shell-form transformer insulation model

To evaluate an appropriate level of ac test voltage for 1000-kV transformers, it is necessary to make an accurate estimation of ac V-t characteristics. For the level of impulse test voltage, V-N characteristics are important to evaluate effects of impulse stress repetition. Since both of the characteristics are dependent on insulation structures and manufacturing processes of transformers, it is important to make accurate simulations on transformer insulation for reliable insulation data. To obtain some of the basic data for 1000-kV transformer test levels, long-time ac V-t tests and impulse V-N tests of up to 1000 times voltage application were carried out on an insulation model simulating fundamental structure of shell-form transformers. The model is composed of a parallel electrodes system with a compound structure of pressboard barrier and oil gap. The tests showed the following characteristics: ac V-t characteristics of up to several ten days could be described by two lines, each representing short-time and long-time characteristics. V-N characteristics of lightning and switching impulse were expressed by relatively flat lines, which showed a decrease in breakdown voltage by less than 10 percent after 1000 times impulse application.     

±1 100 kV特高压直流输电换流阀运行试验研究

随着电网电压等级和传输容量的提高,特高压直流输电工程的电压等级也随之提高, 研发更高电压等级、更高容量直流输电线路及相关设备的需求也更加迫切。为此,国网智能电网研究院完成了±1100 kV特高压直流换流阀的研制。对±1 100 kV特高压直流换流阀运行试验项目和实际试验参数进行全面介绍,阐述了换流阀合成试验方法,并展示了试验波形。试验结果表明,该±1 100 kV/5 000 A特高压直流换流阀样机顺利通过试验考核,设计合理。     

Validating surge test standards by field experience: High-energytests and varistor performance

High-energy surge tests emerging in IEEE and IEC standards are addressed. The results of modeling the application of a surge test to a family of commonly used varistor sizes (14, 20, and 32 mm in diameter) are reported. For each varistor size, the computations were performed for three levels of manufacturing tolerances on the varistor: nominal value, -10%, and +10%. It is concluded that a reexamination of the premises that led to the proposed IEC test specifications is necessary. The proposals in the new version of IEEE C62.41 appear more consistent with field experience     

Dielectric strength of transformer insulation at DC polarityreversal

Among special insulation tests for DC power converter transformers, polarity reversal tests can be substituted by applied AC voltage tests from a stress similarity in oil ducts. In order to investigate equivalent levels of other insulation tests to polarity reversal tests, the dielectric strength of a transformer at polarity reversals was examined by use of a model of typical oil/paper composite insulation. From the comparison of polarity reversal and other insulation tests, it was found that dielectric strength of transformer insulation at polarity reversals is phenomenally similar to that under switching impulse stresses. Equivalent AC test voltage to polarity reversal test was also estimated from the experimental results. The breakdown characteristics of polarity reversal tests showed that partial discharges at polarity reversals impose less harmful stress on insulation barriers than those at usual AC or impulse tests     

Allowance for insulation ageing in the new concept of acceleratedlife tests of high-voltage power transformers

It is pointed out that the existing system of type and acceptance tests of high-voltage transformer insulation does not take into account insulation aging, which is particularly objectionable with respect to equipment with reduced insulation levels. The authors propose a novel concept of accelerated life tests based on integrated simulation of basic operating loads both periodic (surge) and long-term ones, by performing a long-term accelerated test simulating the working conditions, with exposure of the test object and/or its insulation to periodic operating surges (overvoltages and overcurrents). This test replaces a group of conventional individual acceptance tests and provides more ample and more precise information on the performance and dependability of the equipment. The test procedure was checked in a test of a small lot of 1600 kVA 35 kV power transformers     

变压器和组合电器特殊连接方式下的试验方法

针对变压器和组合电器的各种特殊连接方式,提出各设备应在未组装前进行独立试验,组装后进行耐压试验和部分试验项目,保证交接试验质量。并给出了66 kV电压等级变压器和组合电器各种特殊连接方式下的耐压试验方案,对类似现场试验提供指导。     

On-site partial discharge measurements on premoulded cross-bondingjoints of 170 kV XLPE and EPR cables

A total number of 15 premoulded joints of three 170 kV cable circuits (XLPE and EPR) were equipped with partial discharge (PD) sensors. The developed sensors are based on inductive high frequency coupling of partial discharge pulses occurring in the joints. The PD activity of each joint was monitored during an after laying AC acceptance test. The test voltage of 190 kV was generated by means of a frequency-tuned series-resonance test set. The signals of the PD sensors were assessed with a spectrum analyser in a frequency range from 15 to 50 MHz, allowing a good separation of noise from PD signals under high interference levels. The investigation demonstrated the feasibility of on-site PD measurements on joints during after laying tests     

Field motor testing: limiting risk

There are a number of insulation tests that can be applied to an AC winding, which, if applied in a systematic and thoughtful manner, can provide useful information about the condition of a motor's insulation system. The nondestructive tests should always be performed first, followed by go/no-go testing if provision can be made for nondisruptive repair scheduling. While generally nondestructive, misdiagnosis of motor vibration will make it impossible to correct the responsible component. Very often, elevated vibration levels serve as early warnings of a more serious condition. With proper understanding of motor fundamentals and correct test procedures, the service life of a motor can be maximized with the least amount of incurred risk, and, therefore, at minimal cost. The following tests are discussed in this paper: insulation resistance testing, partial discharge testing, DC high potential tests, AC high potential tests, and vibration tests and analysis     

配电终端自动化测试系统的设计与实现

为了提高配电终端的自动化测试效率以及远程测试数据的系统化管理能力,设计了一套配电终端自动化测试系统。该系统包括管控平台和配电终端自动化测试仪(以下简称"测试仪")。其中,管控平台实现了测试标准的统一化及测试数据的自动分析;测试仪实现了配电终端的全自动化检测及测试数据收集与上传。该系统的开发与设计,大大提高了配电终端集成测试和自动化测试水平,有效降低了检测成本和人力成本。该系统在配电终端的现场自动化测试方面具有较高的应用价值。     

New electromagnetic contactor

This paper deals with the design concept and test results of the experimental development phase of a new electromagnetic contactor. The contactor is used for making, switching and breaking of apparatuses and devices at voltage levels up to 1 kV. The use of this contactor will be illustrated in the example of a star-delta starter for induction motors. Currently, starters consist of three contactors, together with its power-, control- and signal connections. An experimental prototype of the new contactor has already been made. Among the tests performed on this prototype are tests for temperature rise limits, dielectric properties and partial tests of mechanical properties. The tests of the rated making and breaking capacities have also been executed. After some constructional modifications, the electromagnetic contactor has successfully passed all the above mentioned tests.     

±1100kV特高压直流输电晶闸管阀运行试验系统设计

为满足我国特高压直流输电发展和建设的需要,提出了满足±1 100kV特高压工程换流阀运行试验系统的设计。根据±1 100kV特高压工程规范,提出了预期运行试验参数,从运行试验系统的一次电气原理设计、二次控制保护设计和测量监测设计3个方面进行讨论和研究,最终通过仿真手段对电气原理和控制系统原理进行了验证。研究结果表明,±1 100kV特高压工程换流阀运行试验系统设计是可行的,可以满足所有运行试验的要求,更加符合换流阀设计的特点,能够达到试验检测目的。该试验回路建成,可以满足±1 100kV工程阀15级串联同时进行运行试验,也将成为世界上容量最大的运行试验回路,可以为我国±1 100kV直流输电工程研发和工程建设提供保障。     

Insulation co-ordination for gas-insulated transmission lines (GIL)

In this paper focus is given to the insulation co-ordination of a closed system with integrated surge arresters. The calculations of transient overvoltages are made with typical applications of the integration of GIL in the 400 kV net of overhead lines. The overvoltages in the system are calculated and discussed for system lengths of 1 km and 10 km. Recommendations for such applications for the insulation levels are given. The GIL design configuration, the lightning overvoltages of overhead lines, and the overvoltages in the GIL are discussed under respect of overvoltage protection measures. Together with the use of surge arresters the insulation levels due to overvoltages are discussed. The insulation co-ordination is a very important measure for system optimization. Calculated values found for the insulation level of the GIL were proven with type tests and long duration test set-ups. Some test results are also explained in this paper     

1 100 kV GIS设备现场交接试验的重点及难点

文章主要介绍了特高压晋东南变电站1 100 kV全封闭组合电器(gas insulated switchgear,GIS)现场交接试验内容。本次交接试验是经过行业专家充分论证后最完整的一次GIS交接试验,由于特高压的特点加大了常规试验的试验难度,构成了本次交接试验的难点,另外在试验示范工程中有些新的、探索性试验项目,如局放监测离线试验、在线监测试验等,构成本次试验的重点。文中着重介绍试验过程中的重点和难点。     

Harmonic measurements made on the upgraded New Zealand inter-islandHVDC transmission system

This paper introduces the upgrade to the New Zealand inter-island HVDC transmission system. It then details the procedure of one of several tests conducted to measure harmonic levels created by the upgraded transmission system. Harmonic levels were measured using the CHART (Continuous Harmonic Analysis in Real-Time) harmonic monitoring instrumentation. The connection of CHART to the high voltage network and its configuration during the test is discussed. A sample of results gathered while monitoring are presented, including characteristic harmonics of the converter, and maximum voltage and current levels up to the 50th harmonic for each of the three AC phases. During the tests one of the two AC harmonic filters was switched out to observe its effect on harmonic levels. It was found that with both AC harmonic filters operating, most harmonic levels were lower than with only one filter operating. However one harmonic level, namely the 4th harmonic, was larger with both filters operating. The paper is concluded with a discussion of the results and of the difficulties encountered in measuring harmonics of very low level     

Recommendations in HV DC testing of MV cable insulation

Research and field reported data supports the theory that high voltage DC testing can reduce the life of both unaged and aged medium-voltage cross-linked polyethylene (XLPE) cable insulation. This research led an industry movement to eliminate factory DC testing, and reduce the field level and frequency of DC testing. DC factory testing identifies an imperfection in the insulation wall as well as mechanical damage. The test sequence in the factory is to perform the AC voltage withstand and corona tests first, followed by the DC withstand test. The AC withstand and corona test levels today are very demanding and locate the same insulation imperfections. Therefore, it can be inferred that today's level of AC withstand and corona testing positively locates insulation imperfections and the following DC testing is redundant and not required. Statistical analysis of factory testing shows that DC testing after AC withstand and corona tests has no additional benefit. The changes and recommendations made by the Association of Edison Illuminating Companies to DC testing are outlined     

移动式高压智能综合测试系统研制与应用

为了确保高压试验人员作业的安全,缩短试验时间,提出了研发移动式高电压智能综合测试系统(试验车)的设想.基于此,阐述了该移动式高电压智能综合测试系统(试验车)设计、研制过程,强调了该系统应集设备试验、状态评估、数据传输、带电测试等功能于一体,并具有测试功能完善、测试精度高、测试速度快、智能化、数字化、操作简捷等特点.实践验证:研制的试验车用于事故抢修、灾害应急、例行试验、特殊试验等,且获得的试验数据满足试验项目要求.     

Design and operational testing on thyristor modules for the SVCKemps Creek

The design and operational testing of valves for the SVC (static Var compensator) to be installed at Kemps Creek substation in Australia are discussed. The most important design principles and features of the thyristor modules are given. Operational tests carried out on the thyristor modules are described; for this test program, noteworthy test circuits have been set up to perform both TSR (thyristor switched reactor) and TSC (thyristor switched capacitor) fault current tests with high test values and special waveforms. Test results and test circuits are presented     

110kV交联电缆及附件的现场变频谐振试验

结合实例重点介绍110kV交联电缆的变频谐振试验,论证试验的有效性,并提出变频谐振试验所需电源容量的估算方法,分析该试验方法的局限性,建议重点发展局部放电、红外成像等非破坏性试验。     

高压电容器内放电电阻的设计与应用思考

内放电电阻是高压电容器的一个很重要部件,它的可靠性和合理选用对电容器的设计来说是一个值得思考的问题。就此问题,通过电阻温度系数试验、出厂试验、型式试验、耐久性试验以及相关实例的计算,综合考虑各种影响因素,尽量使高压电容器内放电电阻的设计与应用更加合理、可靠。     

挤出绝缘高压直流电缆系统试验技术规范综述及建议

高压直流电缆系统的试验标准和技术方法直接决定了对产品可靠性评估的准确性,也间接对电缆结构及运行设计产生影响。概述了国内外针对挤出绝缘直流电缆系统试验的相关技术规范及标准,重点介绍了CIGRE发布的技术手册TB 496中推荐的型式试验和预鉴定试验的方案及要求,以及我国国家电线电缆质量监督检验中心推出的TICW 71-74系列技术规范;还介绍了若干发达国家针对直流电缆系统试验技术所进行的研究及应用,并对有待深入研究的相关课题提出了建议。